* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

a {
  color: black;
  text-decoration: none;
}

a, a:visited, a:link, a:hover {
  color: unset;
}

/*去掉 li 标签的默认样式*/
li {
  list-style: none;
}
